This disclosure relates generally to methods for producing polycarbonate copolymers comprising greater than 45 mole percent of structural units derived from a biphenol. Further, the disclosure relates to use of these polycarbonate copolymers for producing articles that have low haze, good ductility, transparency, and good chemical resistance.
Polycarbonates, such as bisphenol A polycarbonate have excellent mechanical properties, resistance to heat and transparency. They are therefore used in a wide variety of applications like automotive parts, optical storage media, industrial components, and the like. However, there are other applications in industries, such as the medical industry, performance packaging industry, automotive industry, and the like that require in addition to the above-mentioned properties, increased resistance to solvents and other chemicals. As the amount of structural units derived from the biphenol increases, the tendency of the copolymer to crystallize also increases. However, when crystallization sets in, the polymer usually turns hazy or opaque.
Therefore there is a need for effective methods for producing transparent articles comprising biphenol polycarbonate copolymers, which have a higher level of structural units, that is, greater than 45 mole percent of structural units derived from a biphenol. Such copolymers are valuable for producing articles having desirable properties, such as transparency, low haze, good mechanical properties, such as modulus and ductility; low color, and chemical/solvent resistance effective for applications in the medical industry, performance packaging industry, the automotive industry, and the like.